The integrated optical gyroscope, or optical gyroscope on a chip, has been a sought-after commercial and military goal for several years. A new class of chip integrated gyroscope has recently emerged, utilizing stimulated Brillouin scattering (SBS) to generate very narrow optical linewidths, which compensate for the small scale factors available to such small devices. This technology promises navigation-grade accuracy at reduced cost and size, compared to conventional ring laser gyroscopes and fiber optic gyroscopes.
A conventional SBS gyroscope on a chip is an optical waveguide ring resonator that operates based on the Sagnac effect. Brillouin scattering generates narrow lines at predetermined offset frequencies from the pump, and the effect is cascaded to generate as many as three unique and narrow frequency lines or tones. The SBS tones are then directed onto high-speed photodetectors and their beat frequency, which is rotation-sensitive due to their counter-propagating nature, is monitored over time.
However, in conventional SBS gyroscope configurations, the pump laser itself is also used as one of the readout frequencies, and this places a limit on the linewidth of the measured signal.